Department of CSE (Artificial Intelligence and Machine Learning)

BASIC ELECTRICAL ENGINEERING (A8204)

Year: I B. TECH (CSM-B), SEM: I, A.Y:2024-25

Mr. B. Mohan, Assistant Professor, Dept. of EEE.

Hours Per Week Hours Per Semester Credits Assessment Marks

L T P L T P C CIE SEE TOTAL
2 0 0 30 0 0 2 40 60 100

 COURSE OVERVIEW:

 Basic Electrical Engineering course serves as a theoretical foundation aimed at enriching students’
understanding of electric circuits, DC and AC machines, while fostering analytical abilities.

 This course delves into the foundational concepts and methodologies integral to Electrical
Engineering, covering various aspects such as electrical circuits, network theorems, and
operational principles of key components including DC machines (motors and generators),
Transformers, Induction motors, and Synchronous generators.

 COURSE OUTCOMES (COs)

 After the completion of the course, the student will be able to:

CO# Course Outcomes POs

A8204.1 Apply DC circuit principles, network reduction techniques, and 2

theorems to solve Complex DC circuits.

A8204.2 Analyze single-phase AC circuits using sinusoidal waveforms, average 2

and RMS values, and j-notation.

A8204.3 Analyze 1-phae transformer principles, construction, EMF equation, 2

and no-load and on-load conditions.

A8204.4 Analyze the operation and characteristics of DC generators and 2

motors, including EMF and torque equations.

A8204.5 Evaluate the construction, operation, and torque characteristics of 2

three-phase induction motors and synchronous generators.
Syllabus:

DC Circuits: Electrical circuit elements (R, L and C), Ohm’s Law, KVL and KCL, Types of sources, Source
transformation, Network reduction techniques (Series, Parallel and Star-Delta), Mesh and Nodal analysis,
Superposition theorem, Thevenin’s and Norton’s theorems (DC Excitation only) - Numerical problems.

AC Circuits: Representation of sinusoidal waveforms, Average & RMS value, Peak factor, Form factor, j-
notation, Analysis of single-phase AC circuits consisting of R, L, C, RL, RC, RLC combinations (series circuits
only) - Numerical problems.

Single Phase Transformers: Working principle and constructional details, Types-Core and Shell type
transformers, EMF equation, Transformer operation on NO load and ON load Conditions - Numerical
problems on EMF equation.

DC Machines: D.C. Generators - Construction, Principle of operation, E.M.F. equation, Methods of

excitation - Separately excited and Self-excited generators- Numerical problems on EMF equation. D.C
Motors – Principle of operation, Concept of Back E.M.F., Torque equation, Torque-Speed characteristics of
DC Shunt motor - Conceptual description only.

AC Machines: Generation of rotating magnetic fields, Construction and working of a three-phase Induction
motor, Concept of slip, Torque production- Starting and Running torques, Torque-Slip characteristics -
Numerical problems on slip. Construction of Synchronous generator-Salient pole and Non-salient pole
generators, Working principle of synchronous generator, No-Load Characteristics - Conceptual description
only.

 Books and Materials

Text books:

1. William Hart Hayt, Jack Ellsworth Kemmerly, Steven M. Durbin (2007), Engineering Circuit
Analysis, 9th Edition, McGraw-Hill Higher Education, New Delhi, India.
2. B.L. Theraja, A.K. Theraja, A text book of Electrical Technology, (Vol 1&2), S. Chand
Publishers, New Delhi.
Reference Books:

1. D.P. Kothari and I.J. Nagrath, Basic Electrical Engineering, 3rd Edition, Tata Mc-Graw Hill,
2010.

2. D.C. Kulshreshtha, Basic Electrical Engineering, Mc Graw Hill, 2009.

3. L.S. Bobrow, Fundamentals of Electrical Engineering, Oxford University Press, 2011.

 MODULE-I: DC Circuits

 Learning outcomes:
 Basic circuit elements-Types of elements
 Electrical Network and Electrical Circuit
 Electrical circuit elements (R, L and C)
 Types of sources
 Ohm’s Law, KVL and KCL
 Source transformation
 Network reduction techniques (Series, Parallel and Star-Delta)
 Mesh and Nodal analysis
 Superposition theorem
 Thevenin’s and Norton’s theorems (DC Excitation only)
 Numerical problems.
 Basic circuit element- is the basic building block of a circuit.

 Types of Basic circuit elements:

 Linear and Non-linear elements

 Active and Passive elements

 Unilateral and Bilateral elements

 Time variant and Time invariant elements

 Lumped and Distributed elements

 Linear elements: An element is said to be linear, whose V-I characteristics follows only
one equation of a straight line passing through the origin for all.

 In linear circuit, the current is directly proportional to voltage.

 Examples are resistor, capacitor and inductor.

 Non-linear elements: An element is said to be Non-linear whose V-I characteristics are

not linear.

 For example, non-linear resistors, transistors, diodes, vacuum tubes, iron core inductors,
other semiconductor devices, transformers, etc.

 Non-linear elements do not follow the Ohm’s law.

 A non-linear system is that whose parameters change with voltage or current.

 Active Element: The elements which delivers net amount of power to the circuit is called
active element.
 Examples of active elements include voltage source, current source, generators, and
Transistors etc. which control electron flow and amplify signals.

 Active components can amplify and control energy, while passive components cannot
generate or amplify energy, only store or dissipate it.

 Passive Element: The element which receives energy (or absorbs energy) and then either
converts it into heat (R) or stored it in an electric (C) or magnetic (L) field is called passive
element.

 Examples: R, L and C elements.

 Bilateral Element: Conduction of current in both directions in an element with same

magnitude of Resistance or impedance is termed as bilateral element.

 Property of bilateral elements does not change with the change in direction of supply
voltage or current.

 Example: Resistor, capacitor and inductor.

 Unilateral element: Conduction of current in one direction is termed as unilateral

element.
 The property of unilateral elements changes with the change in direction of supply
voltage or current.
 Examples: Diode, Transistor and Rectifiers.

 Time variant and Time invariant elements:

 An element is said to be Time variant, when the V-I characteristics of an elements is

changed with time otherwise time-invariant.

 Lumped elements:

 An element is said to be Lumped, when the size of the electrical element is very small as
compared to the wavelength of voltage and current and its values are concentrated at a
point.
 Examples: Resistor and Inductor.
 Distributed elements:

 An element is said to be Distributed, when the size of the electrical element is

comparable to the wavelength of voltage and current and distributed in space.

 Examples: Transmission line.

 Electrical Network and Electrical Circuit:

 Electrical Network: An electrical network means an interconnection of electrical elements
or electrical components (Resistor, Inductor, Capacitor, Voltage source, Current source).
 An electrical network need not contain a closed path for the flow of electric current.
 It may or may not contain active electrical components.

 Electric Circuit:

 An electric circuit is an electric network that contains a closed path for the flow of electric
current.

 It provides a return path for the current to flow in the circuit.

 In other words, a network that contains active electrical components is known as an electric
circuit.

 It must contain at least one source of energy i.e. active circuit element need to be present
in the circuit.
Note: All electrical circuit is an electrical network, and all electrical network is not electrical

circuit.
 Types of Electric Circuits:

 Open Circuit − If there is a no current flow in the circuit due to any disconnection, the
circuit is called an open circuit.
 Closed Circuit − If there is no discontinuity in the circuit and current can flow in the circuit,
the circuit is called closed circuit.

 Short Circuit − In a DC system, when the positive terminal and negative terminal
connected to each other through a zero-resistance path, it is termed as short circuit.

 In case of AC system, if phase and neutral touches each other or any phase touches the
ground or two phases touches each other, then these conditions are also termed as short
circuit.

 Series Circuit − When circuit elements are connected one after another as the second
end of one element joined to the first end of another element, so that, there is only one
path for the flow of current is available, the resulting circuit is known as series circuit.
 Parallel Circuit − If the circuit elements are connected in such manner that the voltage
across each element is same, the resulting circuit is called as parallel circuit.
 Series–Parallel Circuit − An electric circuit in which some of the circuit components are
connected in the series and some of them in parallel, the circuit is known as series-parallel
circuit.

 Types of Electrical Networks:

 Passive Network − A passive network does not contain any sources of energy.

 They consist only passive circuit elements like resistors, inductors and capacitors etc.
 Active Network − An active network contains one or more sources of energy (like voltage
source or current source), they can supply energy to the network indefinitely. An active
network is also termed as electric circuit.

 Linear Network − In linear circuit, the current is directly proportional to voltage.

 Linear means straight line passing through origin.

 A circuit whose circuit parameters are always constant irrespective of variations in voltage
or current is known as Linear circuit.
 Non–Linear Network −The circuit that contain at least on non-linear element are called
Non-linear Network.

 A Non-Linear circuit means characteristics in between voltage and current are Non-linear.
 A Non-linear circuit is one whose circuit parameters are change with voltage and current.

 Examples are semi-conductor devices (Diodes, BJT and MOSFET etc.)

 Non-Linear circuit doesn’t obey the Ohm’s law.

 Lumped Network- If the network elements can be separated physically from each other,
then they are called as Lumped network.
 Distributed Network- If the network elements like Resistance, Inductance and
Capacitance cannot be physically separable then it is called as Distributed Network.

 Example: Transmission line.

 Unilateral Network-circuit that contain at least one unilateral element are called
Unilateral Network.

 Unilateral circuit allows the current in only one direction.

 Bilateral Network- allows the current flow in both directions. Example. R, L and C.

 Types of sources

Fig. 26 Types of sources.

 Independent Source:

 An independent source is a source that does not dependent on any other quantity in the
circuit.

 Its output voltage or current is set by its own characteristics and remains unchanged
regardless of the load or other circuit conditions.
 Independent Voltage Source: An independent voltage source maintains a specified
voltage across its terminals regardless of the current flowing through it. Example: batteries
or generators.
 Independent Current Source: An independent current source maintains a specified
current through its terminals regardless of the voltage across it. Example: photovoltaic
cells.
 Ideal voltage source:

 Ideal voltage source is a device that produces a constant voltage across its terminals
(VL=VS) no matter what current is drawn from it.

 Terminal voltage (VL) is independent of load (resistance) connected across the terminals.
It has zero resistance.

 The current flowing through the load is given by the expression V L=VS=ILRL and we can
represent the terminal characteristic of an ideal dc voltage as a straight line parallel to the
x-axis.

 Practical voltage source:

 Voltage sources that have some amounts of internal resistance are known as a practical
voltage source.

 Terminal voltage (VL) is dependent on load current.

 The terminal V-I characteristics of the practical voltage source can be described by an
equation

VL=VS-ILRs

 Ideal current source:

 Ideal current source is a device that delivers a constant current to any load resistance
connected across it, no matter what the terminal voltage is developed across the load (i.e.,
independent of the voltage across its terminals).
 It has infinite internal resistance.

 Practical current source:

 Load current depends on load voltage.

 The slope of the curve represents the internal resistance of the source.

 One can apply KCL at the top terminal of the current source.

 Dependent source:

 A dependent source is a source that depends on another quantity in the circuit.

 Its output voltage or current is a function of the voltage or current of another part of the
circuit.

 A dependent source is also called a controlled source.

 If the voltage across an ideal voltage source is determined by some other voltage or current
in a circuit, it is called a dependent or controlled voltage source.
 Dependent voltage sources are represented with the signs ‘+’ and ‘-’ inside a diamond
shape. The magnitude of the voltage source can be represented outside the diamond
shape.

 If the current through an ideal current source is determined by some other voltage or
current in a circuit, it is called a dependent or controlled current source.

 Dependent current sources are represented with an arrow inside a diamond shape. The
magnitude of the current source can be represented outside the diamond shape.
 (a) (b) (c)
(d)

(a) (b) (c)

(d)
Fig. 35 Dependent sources symbol and circuit (a)Voltage controlled voltage source. (b) Current
controlled voltage source. (c) Current controlled current source. (d) Voltage controlled current
source.

 Definitions:
 Current: The current "i" flowing through a conductor is defined as the time rate of flow of
charge. Current is measured in terms of Ampere. Mathematically, it can be written as
𝑑𝑞
𝑖=
𝑑𝑡

𝑞 = ∫ 𝑖 𝑑𝑡

Where, q is the charge, and its unit is Coulomb. t is the time and its unit is second.

 In general, Electron current flows from negative terminal of source to positive terminal,
whereas Conventional current flows from positive terminal of source to negative terminal.
 A direct current (dc) is a current that remains constant with time.

(a) DC current (b) AC current

  Electromotive Force (EMF): Electromotive force, or emf, is the energy required to move
a unit electric charge by an energy source such as a battery, cell, or generator.
 It is defined as the potential difference across the terminals where there is no current
passing through it, i.e., an open circuit with one end positive and the other end negative.
 It is measured in Volt.
 Voltage: The voltage is an electromotive force that causes the charge (electrons) to flow.
Mathematically, it can be written as
𝑑𝑊
𝑉=
𝑑𝑞
𝑊 = ∫ 𝑉 𝑑𝑞

Where, W is the potential energy, and its unit is Joule. q is the charge and its unit is
Coulomb.
 It is measured in terms of Volt.
 As an analogy, electric current can be thought of as the flow of water through a pipe and
Voltage can be thought of as the pressure of water that causes the water to flow through
pipe.

Fig. EMF and Voltage.

 Power: The power, P defined as the time rate of flow of electrical energy.
Mathematically, it can be written as
𝑑𝑊
𝑃=
𝑑𝑡
Where, W is the electrical energy, and it is measured in terms of Joule. t is the time, and
it is measured in seconds.
Above equation can be re written as,
𝑑𝑊 𝑑𝑊 𝑑𝑞
𝑃= = 𝑋 = 𝑉𝐼 .
𝑑𝑡 𝑑𝑞 𝑑𝑡
 Power is nothing but the product of voltage V and current I. Its unit is Watt.
 Passive sign convention is satisfied when the current enters through the positive terminal
of an element and P=+ VI. If the current enters through the negative terminal, P=-VI.

Fig. Passive sign convention.
 The law of conservation of energy must be obeyed in any electric circuit. For this reason,
the algebraic sum of power in a circuit, at any instant of time, must be zero, ∑ 𝑃 = 0.
 Energy (W): Energy is the capacity to do work, measured in joules (J).
𝑑𝑊
𝑃=
𝑑𝑡
𝑊 = ∫ 𝑃 𝑑𝑡 = ∫ 𝑉𝐼 𝑑𝑡
 Ohm’s Law:
It states that at constant temperature current density (J) is directly proportional to the
electric field intensity (E). (Or)
It states that, at constant temperature the current flowing through the conductor is directly
proportional to the voltage across the conductor.

Where, l= length of the conductor, i= current flowing through the conductor and

A= cross sectional area of the conductor.

𝐽𝛼𝐸
𝑖 𝑣
𝛼
𝑎 𝑙
𝑖 𝑣 1
=𝜎 , 𝑤ℎ𝑒𝑟𝑒 𝑐𝑜𝑛𝑑𝑢𝑐𝑡𝑖𝑣𝑖𝑡𝑦, 𝜎 = 𝑎𝑛𝑑 𝜌 − 𝑅𝑒𝑠𝑖𝑠𝑡𝑖𝑣𝑖𝑡𝑦.
𝑎 𝑙 𝜌
𝑖 1𝑣
=
𝑎 𝜌𝑙
𝜌𝑙 𝜌𝑙
𝑣 = 𝑖 = 𝑅𝑖, 𝑤ℎ𝑒𝑟𝑒 𝑅 = .
𝑎 𝑎
𝑣𝛼𝑖
 Ohm’s Law Pie Chart
  Ohm’s Law Matrix Table

 Applications of Ohm’s Law

 To determine the voltage, resistance or current of an electric circuit.
 Ohm’s law maintains the desired voltage drop across the electronic components.
 Ohm’s law is also used in DC ammeter and other DC shunts to divert the current.
 Limitations of Ohm’s Law
 Ohm’s law is not applicable for unilateral electrical elements like diodes and transistors as
they allow the current to flow through in one direction only.
 For non-linear electrical elements with parameters like capacitance, resistance etc the ratio
of voltage and current won’t be constant with respect to time making it difficult to use Ohm’s
law.

 Electrical circuit elements (R, L and C):
  Resistor: Resistor is a two terminal physical device, specified by Resistance R and
measured in the unit of ohm(Ω).
 It is either opposes or restricts the flow of electric current.
 It dissipates the energy in the form of heat.
 Resistors are used to limit the amount of current flow and / or dividing (sharing) voltage.
 It is a linear, passive and bilateral element.

Fig. Symbol of resistor.

 Let the current flowing through the resistor is I amperes and the voltage across it is V
volts. The symbol of resistor along with current, I and voltage, V are shown in the
following figure.

Fig. Basic Resistor element. Fig. V-I characteristics of Resistor.

 According to Ohm’s law, the current flowing through the resistor, R is directly
proportional to the voltage applied. Mathematically, it can be represented as 𝐼 𝛼 𝑉.
1
𝐼 = 𝑅 𝑉 − − − (1)

𝑉 = 𝐼𝑅 − − − (2)
𝑉
𝐼 = 𝑅 − − −(3)

From Equation 3, we can observe that the current flowing through the resistor is directly
proportional to the applied voltage across resistor and inversely proportional to the resistance of
resistor.

 Power in elements R, 𝑃 = 𝑉𝐼 = (𝐼𝑅)𝐼 = 𝐼 2 𝑅 − − − (4)

𝑉 𝑉2
= 𝑉 (𝑅 ) = − − − (5)
𝑅
𝑉2
 𝐸𝑛𝑒𝑟𝑔𝑦 = ∫ 𝑃 𝑑𝑡 = ∫ 𝐼 2 𝑅 𝑑𝑡 = ∫ 𝑑𝑡 − − − (6)
𝑅
 Inductor
 Inductor is a two terminal physical device, specified by inductance (L) and its unit is
Henry.
 It opposes the sudden changes in flow of current through it.
 It stores the energy in electromagnetic field.
 It is a linear, passive and bilateral element.
 When there is a current flow in Inductor, causes the magnetic field (ɸ)setup in it. So,
the amount of total magnetic flux (𝛹 = 𝑁ɸ) produced by an inductor depends on the
current, i flow through it and they have linear relationship. Mathematically, it can be
written as
𝛹𝛼 𝑖 − − − (1)
𝛹 = 𝐿𝑖 − − − (2)

Fig. 𝛹 − 𝑖 𝑐ℎ𝑎𝑟𝑎𝑐𝑡𝑒𝑟𝑖𝑠𝑡𝑖𝑐𝑠 𝑓𝑜𝑟 𝑖𝑛𝑑𝑢𝑐𝑡𝑜𝑟. Fig. Inductor with N-number of turns.

Fig. Symbolic representation of inductor.

 According to Faraday’s laws of electromagnetic induction, there will be voltage induced
the coil.
𝑑𝛹 𝑑(𝑁ɸ) 𝑑(𝐿𝑖) 𝑑𝑖
𝑉𝐿 = 𝑒𝐿 = 𝑑𝑡
= 𝑑𝑡
= 𝑑𝑡
= 𝐿 𝑑𝑡 , 𝑣𝑜𝑙𝑡𝑎𝑔𝑒 𝑎𝑐𝑟𝑜𝑠𝑠 𝑖𝑛𝑑𝑢𝑐𝑡𝑜𝑟.
 1
𝑖= ∫ 𝑉𝐿 𝑑𝑡 , 𝐶𝑢𝑟𝑟𝑒𝑛𝑡 𝑓𝑙𝑜𝑤𝑖𝑛𝑔 𝑡ℎ𝑟𝑜𝑢𝑔ℎ 𝑡ℎ𝑒 𝑖𝑛𝑑𝑢𝑐𝑡𝑜𝑟.
𝐿
𝑑𝑖
 𝑃𝑜𝑤𝑒𝑟 = 𝑉𝑖 = 𝑖 𝐿 𝑑𝑡
𝑑𝑖 1
 𝐸 𝑛𝑒𝑟𝑔𝑦 𝑠𝑡𝑜𝑟𝑒𝑑 𝑖𝑛 𝑖𝑛𝑑𝑢𝑐𝑡𝑜𝑟 = ∫ 𝑃 𝑑𝑡 = ∫ 𝑖 𝐿 𝑑𝑡 𝑑𝑡 = 2 𝐿𝑖 2